Combination locks are commonly used to control access to premises and containers and to control release of chains and other locked-up items by controlling the opening of a closure member, but they are not suitable for overall security. So, although such locks may be employed during the day to allow access to people knowing the code, at night the doors are usually locked with a key. This is because such locks generally do not have a sufficiently large number of combinations for the owner to be confident that the code will not be discovered by chance. Furthermore, they are normally operated by pressing buttons and onlookers can see which combination is selected. An additional drawback is that users sometimes forget the code or transpose the digits of the code.
It is therefore considered desirable to devise a combination lock which can overcome or at least minimize these and/or other problems.